Front-End Electronics Characterization and Inverse Beta Decay Monte Carlo Studies in the JUNO-TAO Experiment

This thesis presents the research activity carried out within the JUNO Collaboration during my PhD studies, with particular focus on the Taishan Antineutrino Observatory (TAO), a satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). The work combines experimental studies on detector instrumentation with Monte Carlo simulations of inverse beta decay events, contributing to the development of technologies and analysis tools for high-precision reactor antineutrino measurements. Neutrino oscillations provided the first clear evidence of physics beyond the Standard Model, demonstrating that neutrinos are massive particles. One of the main open questions in neutrino physics is the determination of the neutrino mass ordering. JUNO has been designed to address this problem through precision measurements of reactor antineutrino oscillations, while TAO is dedicated to the measurement of the unoscillated reactor antineutrino spectrum with unprecedented precision. Located about 44 meters from one of the Taishan nuclear reactor cores, TAO aims to achieve an energy resolution below 2% at 1 MeV through the use of silicon photomultipliers, gadolinium-doped liquid scintillator, and cryogenic detector operation. The first part of this thesis focuses on the characterization of the TAO front-end electronics and silicon photomultipliers. The Roma Tre University group contributed to the development and production of the front-end boards and analog-to-digital converters of the detector readout system. My work involved the experimental characterization of pre-production front-end boards coupled with silicon photomultiplier tiles. Dedicated measurements were performed to evaluate key performance parameters of the readout system, including signal-to-noise ratio, single photoelectron resolution, crosstalk probability, and dark count rate. Since these quantities directly affect the detector energy resolution, the measurements were essential to verify that the front-end electronics satisfied the requirements necessary to achieve the TAO physics goals. I also participated in the large-scale testing campaign of front-end boards and ADCs before their installation in the detector commissioning phase. The second part of the thesis is dedicated to Monte Carlo simulations of inverse beta decay interactions in the TAO detector. These simulations are fundamental for modeling the detector response and for relating the physical properties of the incoming antineutrinos to measurable observables such as the number of detected photoelectrons. The simulation framework was used to investigate detector effects relevant for precision measurements, including energy leakage, detector non-linearity, and energy resolution effects. Particular attention was devoted to the study of the prompt signal generated by the positron produced in inverse beta decay interactions and to the relationship between deposited and reconstructed energy. Overall, this work contributes both to the validation of the TAO detector instrumentation and to the development of simulation studies useful for the interpretation of future experimental data and for the achievement of the physics goals of the JUNO and TAO experiments.